1. Field of the Invention
The present invention relates to an agent for cancer immunotherapy containing bacterial components as an active ingredient, and more particularly, a new agent used independently for cancer patients having immuno-competence. More specifically, the invention relates to a new immunotherapeutic agent capable of preventing recurrence of cancer or generation of secondary cancer including post-operative metastasis, in patients having immuno-competence which can be determined by an ability of inducing interferon-xcex3 (IFN-xcex3) and the like. The invention further relates to a new method for determining immuno-competence of a patient by measuring an ability of inducing IFN-xcex3 and so on, which is used for the present cancer immunotherapy.
2. Prior Art
An agent for cancer immunotherapy containing bacterial components as an active ingredient is known, and particularly, numerous clinical data obtained by the cancer immunotherapy using BCG (Bacille Calmette-Guerin) have been accumulated.
There have been widely reported the results of clinical trials on cancer immunotherapy, in particular, since clinical effects of BCG-immunotherapeutic agents were confirmed by Mathe et al. in acute lymphocytic leukemia and by Molton et al. in melanoma in the latter half of 1960""s. However, since the clinical data have been stochastically analyzed for the survival rates in the randomized controlled trial, ineffective cases have increased in immunotherapy with BCG, resulting in the doubt of its effectiveness. After that, BCG was used only supplementarily in chemotherapy. In addition to BCG, bacteria such as C. parvum, hemolytic Streptococcus, and OK432 have also been used. However, in cancer immunotherapy with those bacteria, some were effective and some were ineffective like BCG, and their effectiveness has not been established yet.
Recently, in BCG-immunotherapy, cell wall skeleton (CWS) prepared from cell walls, obtained by grinding bacterial cells and then fractionating by centrifugation, has been used to make improvements in terms of prevention of side effects and regulation of dose and frequency of administration. Clinical trials for lung cancer, leukemia, stomach cancer and the like using BCG-CWS or N. rubra-CWS were conducted under randomized design by Yamamura et al. of Osaka University and their associates. Though the results showed the stochastically significant prolongation of survival time, it was incomplete as a cancer immunotherapy. At present, an established reputation for such immunotherapeutic agents can be seen in Iwanamikoza, Immunoscience 7, Transplantation Immunity and Tumor Immunity, Feb. 29, 1984, p.302, which reads xe2x80x9cThe results, as already stated have failed to show constant effectiveness as an immunotherapeutic agent, because we obtained adverse, ineffective, or insignificant effect. The major reason, among others, for such inconsistency is attributed to the fact that the statistical significance test was performed between the group in which immunotherapy was used as a supplemental therapy and the group in which immunotherapy was not used as a supplemental therapy. Thus, these results suggest the limit of the immunotherapy which does not exert direct anti-cancer effects.xe2x80x9d
The inventors had doubts about the ways in which the cancer immunotherapy using BCG-CWS has been done in the past, analyzed the problems contained in this immunotherapy, and noticed the fact that such immunotherapy had been conducted together with a therapy which has a strong immuno-suppressive effect, such as anti-cancer drug and radiation. The inventors thought that a combination of immunostimulation therapy using BCG-CWS, N.rubra-CWS and so on, and a chemotherapy having immuno-suppressive effect would offset the characteristics of each therapies, and therefore, the combination contains discrepancy. Then, the inventors considered that, in order to show the effectiveness of the cancer immunotherapy with BCG-CWS, N.rubra-CWS or the like, an establishment of administration method which can easily induce immunostimulation, and selection of patients having suitable immuno-competence would be important.
The inventors have discovered that a therapy with independent use of BCG-CWS alone after the initial treatment has shown excellent therapeutic effects not found in the combination of the therapy with BCG-CWS and chemotherapy (Pro. Japan Acad.,70,Ser.B 205-209(1994)). It was also found that, based on the analysis of peripheral blood from treated patients, patients who showed evident induction of IFN-xcex3 by intradermal administration of BCG-CWS survived in good health, including complete cure, and on the other hand, patients who did not show the induction of IFN-xcex3 died in a short time. The inventors have additionally found that the induction of IFN-xcex3 by inoculation of BCG-CWS directly correlates to anticancer effects (Japanese Cancer Association, 54th Meeting, No.2411, 1995).
According to the above findings, the inventors made extended study in order to establish a cancer immunotherapy using bacterial components alone as an active ingredient. As a result, it was found that CD28 as well as IFN-xcex3 and G-CSF are useful as a marker of immuno-competence after inoculation of bacterial components in order to recognize a patient who has immuno-competence suitable for the present therapy. The inventors also discovered that an initial therapy has a great influence on the maintenance of an appropriate immuno-competence of a patient, and selection of such initial therapy is of great importance.
The present invention is based on the above findings.
The cancer immunotherapy which has been established by the present invention is summarized as follows.
The immunotherapy with BCG-CWS and the like is effective, as a matter of course, only in patients who have immuno-competence. Since the immuno-competence is affected by initial therapy to be used, it is essential that the therapy with independent use of BCG-CWS alone should be performed after removing as much cancer cells as possible by, for example, surgical operation, and discontinuing a chemotherapy or radiation which possibly decreases immuno-competence of patients.
Upon inoculation of BCG-CWS, a series of transient alterations are observed in components of peripheral blood from a patient. The alterations closely relate to the effectiveness of the immunotherapy as follows:
(1) Alterations in components of peripheral blood from a patient to whom the immunotherapy was effective.
As for cellular components, increase in leukocytes, particularly increase in granulocytes, and decrease in lymphocytes (continue about 24 hours) are found, with the increase and decrease having their peaks at from about 15 hours to about 18 hours after inoculation.
As for cytokines, increase in IFN-xcex3 (continues about 30 hours) and G-CSF (continues about 1 week) is found.
As for markers on the surface of T cell, increase in high CD28-positive lymphocytes (continues about 4-6 weeks) is found.
(2) Alterations in components of peripheral blood from patients to whom immunotherapy was not effective.
No alteration of cellular components, cytokines, or markers on the surface of T-cell was found.
In three patients to whom immunothrapy was effective, increase of CD28-positive lymphocytes was not found. At the beginning of the therapy, those patients continued to show recovery. However, metastasis to the brain was found around after 2 years in two patients and they eventually died.
Accordingly, we considered that IFN-xcex3 and CD28 are useful as markers to know immuno-competence which gives anticipation on the results of the therapy. Influence of pre-treatment including initial therapy on the immuno-competence was investigated, especially in terms of inducibility of IFN-xcex3, to give the following findings.
(1) In about 90% of the patients who did not receive any pre-treatment, such as chemotherapy and radiation therapy, which may influence to immuno-competence, induction of IFN-xcex3 was observed owing to a therapy with independent use of BCG-CWS alone.
(2) In only about 30% of the patients who received pre-treatment, such as chemotherapy and radiation therapy, which influences to immuno-competence, induction of IFN-xcex3 was observed owing to a therapy with independent use of BCG-CWS alone.
(3) Great difference that was observed in the survival rates is as follows: About 90% of the patients who were positive in IFN-xcex3 induction survived more than 6 months after the beginning of the treatment with BCG-CWS. On the other hand, only about 20% of the negative patients who failed to induce IFN-xcex3, survived more than 6 months after the beginning of the treatment with BCG-CWS.
Accordingly, it has been demonstrated that a therapy with independent use of BCG-CWS alone is desirable as a cancer immunotherapy after removing as much cancer cells as possible by surgical operation, and discontinuing therapy with chemotherapy and radiation which are considered to decrease immuno-competence.
On the basis of the above findings, the present invention has been completed, which is summarized as follows:
(1) An agent for cancer immunotherapy with independent use, which contains bacterial components as an active ingredient, said components inducing immuno-competence in a cancer patient when administered intracutaneously, said immuno-competence being detectable by increases of IFN-xcex3 and a population of high CD28-positive lymphocytes in blood-level.
(2) An agent for cancer immunotherapy as stated in Item (1), characterized by that said agent is to be administered to the following patients and suppresses recurrence of the cancer or occurrence of secondary cancer:
(a) a patient who is not suffering from lowering of immuno-competence, and
(b) a patient who does not have distant metastasis including that in the brain, liver, or bone.
(3) An agent for cancer immunotherapy as stated in Item (2), characterized by that said agent is to be administered to a cancer patient who has had remission induction or operation for removing primary lesion on initial therapy.
(4) An agent for cancer immunotherapy as stated in Item (3), wherein the patient is the one having solid cancer, and the initial therapy is a surgical operation.
(5) An agent for cancer immunotherapy as stated in Item (3), wherein the patient is the one having non-solid cancer, and the initial therapy is chemotherapy.
(6) An agent for cancer immunotherapy as stated in Item (1), characterized by treating metastasis of cancer to the lymph node.
(7) An agent for cancer immunotherapy as stated in Item (1), wherein the patient is the one suffering from lung cancer.
(8) A method of testing immuno-competence in an immunotherapy with independent use, comprising determining the level of IFN-xcex3 and CD28 marker in blood obtained from a cancer patient who were administered bacterial components intracutaneously.
The first embodiment of the invention is an agent for cancer immunotherapy with independent use containing bacterial components as an effective ingredient. As the bacterial components, a known adjuvant for anti-cancer immunity is applicable (see Iwanamikoza, Immuno Science 7,p.265, Table 5.2, 1984). For example, BCG-CWS, N.rubra-CWS, and the like are preferable, and BCG-CWS is more preferable.
An agent for cancer immunotherapy with independent use according to the present invention is preferably administered to a patient, in which the agent induces immuno-competence when administered intracutaneously, said immuno-competence being detectable by increases in blood level of IFN-xcex3 and CD28 markers in the patient.
An agent for cancer immunotherapy with independent use according to the present invention is a non-specific immunotherapeutic agent, and therefore, may be applied to any sorts of cancers, for example, lung cancer, stomach cancer, colon cancer, breast cancer, lingual cancer, laryngeal cancer, acute myelocytic leukemia, pancreatic carcinoma, ovarian cancer, and the like.
Up to now, the agent for cancer immunotherapy with independent use according to the present invention was administered to 181 cancer patients, and among them the number of the patients suffering from lung cancer was the largest (75 patients). The patients tested covered almost all sorts of cancers, including stomach cancer, colon cancer, breast cancer, etc.
The second embodiment of the invention shows that the following patients are preferable as a subject to which the agent for cancer immunotherapy according to the invention is applied:
(a) a patient who is not suffering from lowering of immuno-competence, and
(b) a patient who does not have distant metastasis including that in the brain, liver, bone, or the like.
In addition, the agent for cancer immunotherapy according to the invention can be used as a continued maintenance therapy to suppress recurrence of the cancer including metastasis or occurrence of secondary cancer.
In the third embodiment of the invention, the agent for cancer immunotherapy according to the invention is preferably administered to a patient suffering from acute myelocytic leukemia who has had remission induction, or a patient suffering from a cancer who has received operation for removing primary lesion during initial therapy.
In the fourth embodiment of the invention, an agent for cancer immunotherapy of the invention is preferably administered alone to a patient having a solid cancer who received operation for removing primary lesion as much as possible. The solid cancer includes lung cancer, stomach cancer, colon cancer, and so on. Lung cancer is preferable.
In the fifth embodiment of the invention, an agent for cancer immunotherapy of the invention is preferably administered to a patient having a non-solid cancer who had remission induction by chemotherapy in initial therapy. The non-solid cancer includes leukemia and the like, and preferably, acute myelocytic leukemia.
In the sixth embodiment of the invention, an agent for cancer immunotherapy of the invention suppresses metastasis of cancer from primary lesion, and it is effective particularly to a cancer which has metastasized in the lymph node. The agent is significantly effective to an immuno-competent patient who showed IFN-xcex3 induction, and the treatment with the agent resulted in disappearance of a fairly large metastasis in the lymph node. It was demonstrated that the agent is poorly effective to a patient who has had metastasis of cancer in the liver, brain, bone, and the like, before the beginning of the immunotherapy, even if the agent could induce IFN-xcex3 in the patient. The reason why the agent for cancer immunotherapy of the invention, particularly, the immunotherapeutic agent comprising BCG-CWS, is effective to metastasis of cancer in the lymph node would be that an activation of a cytotoxic T lymphocyte (CTL) which acts specific to particular cancers is directly related to CD28 marker. That is, an increase in CD28 marker means an increase in a population of high CD28-positive lymphocytes, i.e., an activation of cancer-specific CTL.
In the seventh embodiment of the invention, an agent for cancer immunotherapy of the invention is used for a patient suffering from lung cancer. As will be stated below, therapeutic effects of the agent of the invention were analyzed in detail about a group of patients suffering from lung cancer, which is the largest group among the cases we have handled.
The eighth embodiment of the invention is a method of testing peripheral blood in order to select a patient suitable for the administration of the agent for cancer immunotherapy of the invention. Specifically, in a method of determining whether or not a patient has an ability of IFN-xcex3 induction, blood samples are obtained, before and 18 hours after inoculation of 100xcex3 or 200xcex3 of BCG-CWS, and IFN-xcex3 level in peripheral blood is measured to determine whether IFN-xcex3 induction is positive or not. Suitable time when the above determination is performed may be when the fourth sensitization is conducted, during which BCG-CWS induces immune response, and when the first treatment is conducted, which permits earlier determination as to whether the immunotherapy should be continued or not. A population of high CD28-positive lymphocytes in peripheral blood may be determined according to any known method, for example, flow cytometry.
In addition, according to this embodiment, there are provided not only a method of detecting a cancer patient to whom the independent immunotherapy is applicable as a continued maintenance therapy for cancer that follows an initial therapy, but also a method of detecting a patient to whom the immunotherapy is not suitable and other therapies should be applied. According to this embodiment of the invention, surgical operation followed by an immunotherapy with independent use of BCG-CWS alone can be applied to a patient who can induce IFN-xcex3, and other therapy can be applied at early stage to a patient who cannot induce IFN-xcex3. Thus, an appropriate therapeutic program following initial therapy can be established depending on immuno-competence of a patient.
Preparation of BCG-CWS Inoculant
BCG-CWS may be prepared according to the method described in Azuma et al., J. Natl.Cancer Inst. 52:95-101 (1974).
BCG-CWS inoculant may be prepared according to the method described in Hayashi, A, Proc. Japan Acad.,70, Ser.B (1994)
Namely, BCG-CWS powder is placed in a 5 mL grinder tube, mineral oil (Drakeol-6VR; Pennsylvania Refining Co., Butler, U.S.A.) is added into the tube at the ratio of one drop per mg of BCG-CWS using 26G of injection needle, and then, the mixture was ground to smooth paste. 1.1% Tween 80 solution in saline is added to the mixture, which is then homogenized. The final concentration of a uniform suspension of small oil droplets containing BCG-CWS is 1 mg/mL. The oil attached BCG-CWS suspension was sterilized by incubating at 60xc2x0 C. for 30 minutes.
Inoculation Schedule
Throughout the present study, BCG-CWS is always inoculated alone.
The inoculation schedule is divided into sensitization phase and therapeutic phase. In the sensitization phase, usually 200xcex3 of BCG-CWS is intracutaneously inoculated once a week, totally four times, at the right and left lateral brachiums alternately. In the therapeutic phase, interval of the inoculations is extended to every four weeks. The amount of BCG-CWS to be inoculated is selected from between 10 and 250xcex3, preferably between 25 and 200xcex3, depending on biological responses of a patient.
Biological Response as an Index for Determining the
Amount of BCG-CWS to be Administered
Biological responses as an index for determining the amount of BCG-CWS to be administered are classified to local biological responses and systemic biological responses.
(1) Local Biological Responses
Primary local biological responses include skin reactions at the spot of injection. Specifically, they are flare, induration, and formation of ulcer. Swelling of the local lymph node, i.e., lymphangitis and lymphadenitis extending from the injection spot to the attending lymph node may occur occasionally, but it is always transient.
(2) Systemic Biological Response
The following transient over-response may occur due to interaction between the sensitivity of a patient and the amount of BCG-CWS inoculated, although it can be reduced by decreasing the amount of BCG-CWS to be inoculated.
Clinical symptoms: general malaise, fever, anorexia, and sometimes, nausea and vomiting.
Clinical test: leukocytosis, increased C reactive protein (CRP), and sometimes, slightly increased GOT and GPT.
In the case of a patient who does not show the local and systemic biological responses mentioned above, therapeutic effects of immunotherapy with BCG-CWS can not be expected.
Determination of Inductivity of IFN-xcex3
Effects of immunotherapy with BCG-CWS can be predicted by determining inductivity of IFN-xcex3.
Such determination is performed at the fourth inoculation in the sensitization phase (S4) and at the first inoculation in the therapeutic phase (T1). Peripheral blood is obtained before, and 18 hours after inoculation of BCG-CWS, and the blood level of IFN-xcex3 is determined. When the level of IFN-xcex3 increases more than 35 pg/mL by inoculation of BCG-CWS, induction of IFN-xcex3 is judged as positive.
Determination of Induction of CD28-positive T-cells
Effects of immunotherapy with BCG-CWS can be predicted by determining induction of CD28 in the similar manner stated above.
Peripheral blood is obtained before, and 18 hours after inoculation of BCG-CWS, and increase in a population of high CD28-positive lymphocytes in the blood is determined.